The present invention is directed to a valve type musical instrument and method therefor and more specifically to an apparatus and method for accurately adjusting the upstroke and downstroke of the valves of the instrument to provide for improved playing response.
In valve type brass instruments such as the trumpet, the length of the air column is increased by tubing switched in by the use of valves. In the case of a piston type valve the upstroke and downstroke of the piston must conform to tolerances of a few thousandths of an inch. Present musical instruments utilize felt pads or pads of other artificial material for both adjusting the upstroke and downstroke and providing for elimination of any metal clicking sound when the instrument's valves are actuated by the player.
Improper alignment of the valve ports in either the upstroke or downstroke positions can result in a rough or "stuffed" playing characteristic of the instrument and also cause faulty intonation.
Improper alignment may result from faulty manufacturing techniques at the factory where an instrument not built perfectly may be set in a compromising position to play at its optimum. Also long use of the instrument may cause the pad to be pounded thin changing alignment. Where this occurs the changing of the felt pads is possible but this is cumbersome and provides only very coarse adjustment. To somewhat compensate for the decrease in thickness, most manufacturers use pads of a larger size (initially resulting in imperfect playing response) assuming the pads will be pounded down to a better position. In any case, new pads may vary 0.003 to 0.005 of an inch from their nominal size.
Yet another difficulty in the adjustment of valve type instruments is that their design is still based on empirical selection of musically desirable forms. Thus, a dimensionally perfect instrument which also has its ports in perfect alignment may not result in the proper playing response.